A contact pad includes a solder-wettable porous network (310) which wicks the molten solder (130) and thus restricts the lateral spread of the solder, thus preventing solder bridging between adjacent contact pads.

The present invention relates generally to flip chip technology and more particularly, to a method and structure for reducing internal packaging stresses, improving adhesion properties, and reducing thermal resistance in flip chip packages by using more than one underfill material deposited in different regions of the flip chip interface. According to one embodiment, a method of forming a first underfill in an interior region of an interface such that a periphery region of the interface remains open, and forming a second underfill in the periphery region is disclosed.

A method for producing a structure by direct bonding of two elements, the method including: production of the elements to be assembled and assembly of the elements. The production of the elements to be assembled includes: deposition on a substrate of a TiN layer by physical vapor deposition, and deposition of a copper layer on the TiN layer. The assembly of the elements includes: polishing the surfaces of the copper layers intended to come into contact so that they have a roughness of less than 1 nm RMS and hydrophilic properties, bringing the surfaces into contact, and storing the structure at atmospheric pressure and at ambient temperature.